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Seagate picks LSI for flash controller

SSD System-on-Chip designs

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Aspiring solid state drive (SSD) shipper Seagate has picked LSI to supply it with controller silicon for its SSDs.

LSI supplies System-on-Chip (SoC) technology - custom silicon chips - to Seagate and others to control hard disk drives and their I/O (pictured below). They are placed inside the drive enclosure. They read signals from the drive, check for and correct any errors, package up the data bits and deliver them through SAS or Fibre Channel interfaces, via a DRAM buffer, to waiting host computers. These include storage array controllers, PCs and servers. Data coming the other way is passed through the SoC to the hard drive.

Typically there are two ARM microprocessors in an LSI SoC: one to control the drive's servo motor and the other to manage data flow to and from the host interface.

There is no need for servo motor control in an SSD with NAND chips, but there is a need to manage the placement of data on the chips and the wear-levelling needed to maximise NAND chip life. The SSD SoC will also contribute to the SSD's read and write rates.

Seagate has awarded multiple contracts to LSI for notebook, desktop and enterprise hard drive SoCs. It has gone to the same company for its SSD controllers. The Seagate SSD is expected to ship in 2009, with LSI talking cryptically of "two future generations of SoC designs targeting the enterprise space that were previously awarded to LSI and are expected to ship in 2010".

Seagate could have gone to suppliers with proven SSD controller skills, such as STEC, which supplies EMC, or Marvell, which supplies notebook SSD controllers. Instead it has gone to a supplier it knows very well for HDD SoCs but which is untested on flash drive SoCs, though it has produced HBAs for an iGLASS SSD application. It's a big bet by Seagate. ®